The Transformers have changed shape into a slightly less powerful box office contender in its first showings. "Transformers: Dark of the Moon," the third movie in Paramount Pictures' blockbuster robot action series, collected $13.5 million from early screenings Tuesday night.

Of that total, $5.5 million was from 9 p.m. shows at about 2,700 locations with 3-D screens, and an additional $8 million came from 3-D and 2-D screenings at 3,000 theaters at or soon after midnight.

That's less than the $16.6 million 2009's "Transformers: Revenge of the Fallen" grossed from midnight shows alone on a Tuesday night. The decline in attendance is even higher, however, for "Dark of the Moon" when considering the premium 3-D ticket prices.

Still, $13.5 million is a strong start for late-night screenings, particularly on a Tuesday. "The Hangover Part II," currently the year's most successful movie at the domestic box office, generated $10.4 million from opening midnight screenings. "Pirates of the Caribbean: On Stranger Tides," the year's No. 2 movie, took in $4.7 million.

Pre-release surveys had indicated that consumer interest in "Dark of the Moon," which cost about $200 million to produce, was lower than for "Revenge of the Fallen." Through Monday, the Fourth of July, the new movie will likely have a tough time matching the $215 million that its predescessor grossed in its first six full days.

There could be better word-of-mouth for the film as reviews for the third "Transformers" have been better than those for the second, although they're still largely negative.

The movie also opens in most foreign countries this week.

[For the record, June 30, 7:20 a.m.: An previous version of this post incorrectly titled the latest "Transformers" movie as "Dark Side of the Moon."]